Whothe heck works out in thenude? Heidi Northcott and Chuck Liddell, apparently.Heidi Northcott — who’s Lidell’s girlfriend — and the mixed martial artist appear to be nude in a clip posted at the Big Lead.

According to TMZ, “the UFC badass and Heidi Northcott agreed to do the revealing workout for a viral campaign for Reebok — a company that Chuck already has a sponsorship deal with.”